1. Field of the Invention
Embodiments relate to a photographing apparatus and a photographing method, and more particularly, to a photographing apparatus including an image pickup device having a plurality of pixels arranged in a matrix form, and a photographing method thereof.
2. Description of the Related Art
Japanese Patent Laid-Open Gazette No. H11-41523 (hereinafter, referred to as Cited Reference 1) discloses a photographing apparatus equipped with a complementary metal-oxide semiconductor (CMOS) type image pickup device, wherein a front curtain of a shutter operation is performed by using an electronic shutter and a rear curtain of the shutter operation is performed by using a mechanical shutter. Also, Japanese Patent Laid-Open Gazette No. 2007-159061 and Japanese Patent Laid-Open Gazette No. 2007-53742 (hereinafter, respectively referred to as Cited References 2 and 3) disclose a technology for preventing an exposure spot occurring from a difference between lens types, iris values, or shutter speeds, by changing a timing of starting charge accumulation in every area or line in a method of mixing an electronic shutter and a mechanical shutter.
Cited References 2 and 3 aim to compensate for an imagery defect generated by replacing a conventional mechanical front curtain with an electronic reset function. Thus, an operation timing of an electronic shutter constituting a front curtain is set to have almost the same characteristics as an operation timing of a mechanical shutter constituting a rear curtain. In addition, an operation timing is set considering compensation parameters with respect to causes that change shutter characteristics, such as a lens type and an iris value.
However, a dynamic range of a conventional image pickup device is still narrow, and thus it is difficult to reproduce a dark place and a bright place in an image. For example, when a person is to be photographed with a bright blue sky as a background, the sky is saturated and is not reproduced due to over-exposure if exposure is focused on the person. Alternatively, if the exposure is focused on the sky, the person may be photographed in black due to underexposure.
The electronic shutter operates as a front curtain of a shutter that starts exposure of an image pickup device by discharging charges accumulated in the image pickup device. Here, if a time taken to discharge the charges is not sufficient, an afterimage is generated due to remaining charges. Generally, a sufficient discharging time is set to completely discharge the charges so that the afterimage is not generated. However, since the remaining charges may be deliberately generated so as to obtain a long exposure effect, obtaining a good image having a wide dynamic range may be required by adjusting a time taken to discharge the charged for every area or line.